KR20180118071A - Poly(amide-imide) copolymer, article including poly(amide-imede) copolymer, and display device including the same - Google Patents

Abstract

Provided are a poly(amide-imide) copolymer, a molded article comprising the poly(amide-imide) copolymer, a window for a display device including a polymer film including the poly(amide-imide) copolymer, and a display device including the molded article. The poly(amide-imide) copolymer comprises a reactant of at least one tetracarboxylic acid dianhydride, at least one diamine, and at least one dicarboxylic acid derivative, wherein the at least one tetracarboxylic acid dianhydride includes a tetracarboxylic acid dianhydride represented by chemical formula 1, the at least one diamine includes a diamine represented by chemical formula 2, NH_2-R^2-NH_2, and the at least one dicarboxylic acid derivative includes a dicarboxylic acid derivative represented by chemical formula 3. In the chemical formulas 1 to 3, each of R^1 to R^3, X^1, and X^2 is the same as defined in the detailed description of the invention.

Description

TECHNICAL FIELD [0001] The present invention relates to a molded article comprising a poly (amide-imide) copolymer, a poly (amide-imide) copolymer, and a display device (POLY (AMIDE-IMIDE) COPOLYMER, ARTICLE INCLUDING POLY (AMIDE-IMIDE) COPOLYMER, AND DISPLAY DEVICE INCLUDING THE SAME}

The present disclosure relates to a molded article comprising a poly (amide-imide) copolymer, a poly (amide-imide) copolymer, and a display device comprising the molded article of the poly (amide-imide) copolymer.

There is an increasing need for a flexible display that is light, lightweight, thin, light like paper, and flexible, regardless of place and time, as a display that visualizes various information and transmits it to human beings in accordance with the deepening and popularization of informatization have. Flexible substrates, organic and inorganic materials for low-temperature processes, flexible electronics, encapsulation, and packaging technologies are required to realize flexible displays.

Transparent plastic films that can replace conventional window cover glasses for application to flexible displays must meet high hardness and optical properties.

The hardness can be compensated for by coating the hard coat layer, but in this case also, the higher the tensile modulus of the base film (hereinafter referred to as the 'modulus of elasticity') helps to increase the hardness of the final film.

The required optical properties include high light transmittance, low haze, low Yellowness Index (YI), and UV curability.

One embodiment is to provide a poly (amide-imide) copolymer having improved mechanical properties while maintaining high optical properties.

Another embodiment is to provide a molded article comprising the poly (amide-imide) copolymer.

Another embodiment is to provide a display device comprising the poly (amide-imide) copolymer.

An embodiment includes a reaction product of at least one tetracarboxylic dianhydride, at least one diamine, and at least one dicarboxylic acid derivative, wherein the tetracarboxylic dianhydride has the formula Tetracarboxylic acid dianhydride, and the diamine comprises a diamine represented by the following formula (2), and the dicarboxylic acid derivative is a poly (amide-imide Lt; / RTI > copolymer.

[Chemical Formula 1]

In Formula 1, R ¹ is a substituted or unsubstituted quadrivalent C4 to C12 saturated or unsaturated aliphatic hydrocarbon ring group;

(2)

NH ₂ -R ² -NH ₂

In Formula 2,

R ² comprises at least two substituted or unsubstituted C 6 to C 30 aromatic hydrocarbon ring groups, and the at least two substituted or unsubstituted aromatic hydrocarbon ring groups are those in which at least two aromatic rings are replaced by -O-, -S-, -C (= O ) -, -CH (OH) - , -S (= O) 2 -, - (CH 2) p - ( _{where, 1≤p≤10), - (CF 2} ) q - ( wherein, 1≤q≤ _{10), -Si (C n H} 2n + 1) 2 -, -C (C n H 2n + 1) 2 -, -C (C n F 2n + 1) 2 - ( wherein, 1≤n≤10) , -C (= O) NH-, or a combination thereof;

(3)

In Formula 3,

R ³ includes a substituted or unsubstituted C6 to C30 aromatic hydrocarbon ring group, and the aromatic hydrocarbon ring group may include one aromatic hydrocarbon ring, or may include a ring in which two or more aromatic hydrocarbon rings are condensed, or two or more aromatic hydrocarbons a ring or one or more aromatic hydrocarbon ring and the condensed ring at least one single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, - (CH _{2) p} - _{(where, 1≤p≤10), - (CF 2} ) q - ( _{where, 1≤q≤10), -Si (C n} H 2n + 1) 2 -, -C (C _n H _{2n + 1} ) ₂ -, -C (C _n F _{2n + 1} ) ₂ - wherein _{1? n?} 10, -C (= O) NH- or a combination thereof,

X ¹ and X ² are each independently a halogen, a hydroxyl group, or an alkoxy group having from 1 to 4 carbon atoms.

R ¹ in Formula 1 is an unsubstituted C4 to C8 tetravalent saturated aliphatic hydrocarbon ring group.

R ² in Formula 2 is a group in which two or more substituted or unsubstituted phenylene groups are linked by -O-, -S-, -C (= O) - or -CH (OH) -, or more phenyl groups each _{independently, -OH, -CF 3, -CCl 3} , -CBr 3, -CI 3, -NO 2, -CN, -COCH _3, and from the group consisting of -CO ₂ C ₂ H ₅ Substituted by a substituent selected.

The diamine may further comprise a diamine represented by the following formula (2A): < EMI ID =

(2A)

NH _{2 -} R ^{2 '-} NH ₂

In the above formula (2A)

R ^{2 '} includes a group in which two or more substituted or unsubstituted C6 to C30 aromatic hydrocarbon rings are connected by a single bond.

R ^{2 '} in formula (2A) may be a group in which two or more phenylene groups each substituted with -CF ₃ , -CCl ₃ , or -CBr ₃ are linked by a single bond.

Wherein the one or more diamines include a diamine represented by the formula (2A) and a diamine represented by the formula (2), and the R ^{2 '} of the diamine represented by the formula (2A) is -CF ₃ , -CCl ₃ , or -CBr ₃ R ² of the diamine represented by the formula (2) is a structure in which two or more unsubstituted phenylene groups are replaced by -O-, -S-, -C (= O) -, or - CH (OH) -. ≪ / RTI >

Wherein the at least one diamine comprises the diamine represented by the formula (2A) and the diamine represented by the formula (2), R ^{2 '} in the formula (2A) is a structure in which two phenylene groups substituted with -CF ₃ are connected by a single bond, R ² of the diamine represented by the general formula (2) may be such that two unsubstituted phenylene groups are linked by -O-.

In the diamine, the diamine represented by the formula (2) may contain less than the diamine represented by the formula (2A).

In the diamine, the diamine represented by Formula 2 and the diamine represented by Formula 2A may be contained in a molar ratio of 30:70 to 1:99.

The diamine represented by Formula 2 may be contained in an amount of 30 mol% or less based on the total amount of the diamine.

The diamine represented by the general formula (2) may be contained in an amount of 20 mol% or less based on the total amount of the diamine.

The diamine represented by the general formula (2) may be contained in an amount of 10 mol% or less based on the total amount of the diamine.

R ³ in Formula 3 is an unsubstituted phenylene group, and each of X ¹ and X ² may independently be -Cl, -OH, or -OCH ₃ .

R ¹ in Formula 1 is an unsubstituted C 4 saturated aliphatic hydrocarbon ring group.

The poly (amide-imide) copolymer is a product obtained by reacting the tetracarboxylic dianhydride, the diamine, and the dicarboxylic acid derivative at a molar ratio of 40 to 80: 100: 60 to 20, respectively.

The poly (amide-imide) copolymer is a product obtained by reacting the tetracarboxylic dianhydride, the diamine, and the dicarboxylic acid derivative in a molar ratio of 50 to 70: 100: 50 to 30, respectively.

Another embodiment provides a molded article comprising a poly (amide-imide) copolymer according to this embodiment.

The molded article is a film having a tensile modulus of 6.5 GPa or more at a thickness of 50 to 100 탆 and a transmittance of 87.5% or more at a wavelength of 350 nm to 750 nm.

Another embodiment provides a window for a display device comprising a polymeric film comprising a poly (amide-imide) copolymer according to one embodiment.

Another embodiment provides a display device including the molded article.

The display device is a flexible display device.

The poly (amide-imide) copolymer film according to one embodiment is improved in mechanical properties such as tensile modulus while maintaining excellent optical characteristics, and can be usefully used for a display device, particularly, a window film of a flexible display device.

1 is a cross-sectional view of a display device according to an embodiment.
2 is a cross-sectional view of a display device according to another embodiment.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Unless otherwise specified herein, " substituted " or " substituted " means that at least one hydrogen atom of a functional group within a given formula is replaced by a halogen atom (F, Br, Cl or I), a hydroxyl group, a cyano group, amino group {NH _2, and NH (R ^100), or ^{N (R 101) (R 102} ), wherein R ^100, R ¹⁰¹ and R ¹⁰² are the same or different, being each independently selected from C1 to C10 alkyl group}, amidino A C1 to C30 acyl group, a C1 to C30 alkyl group, a C2 to C30 alkenyl group, a C2 to C30 alkynyl group, a C3 to C30 cycloalkyl group, a C3 to C30 cycloalkenyl group, a C3 to C30 cycloalkenyl group, A C6 to C30 aryl group, and a C2 to C30 heterocyclic group, and the substituents may be connected to each other to form a ring.

The "C2 to C30 alkenyl group" means a C2 to C30 alkenyl group having at least one double bond, specifically, a C2 to C18 alkenyl group, and the "C2 to C30 alkynyl group" A C2 to C30 alkynyl group, particularly a C2 to C18 alkynyl group, including a bond.

The "C2 to C30 heterocyclic group" includes at least one hetero atom selected from the group consisting of O, S, N, P, Si and a combination thereof in one ring, for example, A C2 to C30 heteroaliphatic ring group, or a C2 to C30 heteroaromatic ring group.

&Quot; Combination " as used herein, unless otherwise specified, means mixing or copolymerization.

In the present specification, " * " means a part connected to another atom or a functional group.

Research is underway to convert mobile devices such as smartphones and tablet PCs into mobile devices that can be bent, bent, and bent. Therefore, there is a need for a window film for display which can be replaced with a rigid glass at the uppermost stage of the mobile device, and which can be bent, and has a high hardness and a clear display.

For use as a window film, it must meet high hardness and optical properties. The required optical properties include high transmittance, low haze, and low yellow index (YI). The hardness can be compensated for by introducing a hard coating layer, but the tensile modulus of the base film itself must be high to increase the hardness of the final film.

The polyimide or poly (amide-imide) copolymer has excellent mechanical properties, thermal properties, and optical properties and is widely used as a substrate for display devices such as organic light emitting diodes (OLED) and liquid crystal displays (LCD). In order to use such a polyimide or poly (amide-imide) copolymer film as a window film for a flexible display, it is necessary to improve mechanical properties such as hardness or elastic modulus, and optical properties such as transmittance and low yellow index (YI) . However, since the elastic modulus and YI of the polyimide or poly (amide-imide) copolymer have a trade-off relationship with each other, it is difficult to simultaneously improve these two properties.

As a method for enhancing the mechanical properties of a poly (amide-amide) copolymer, there is an attempt to increase the content of the amide structural unit or to prepare a copolymer including a dianhydride having a more rigid structure, In this case, the improvement in the modulus of elasticity is insufficient, and the optical characteristics such as yellowiness (YI) may deteriorate.

Accordingly, the inventors of the present invention have made efforts to develop a composition for preparing a new poly (amide-imide) copolymer which can further improve mechanical properties such as tensile modulus while maintaining excellent optical properties of a poly (amide-imide) I tried. As a result, it has been found that, in a composition for producing a poly (amide-imide) copolymer prepared by reacting a dianhydride with a diamine and a dicarboxylic acid derivative, the composition contains an aliphatic acid dianhydride as a dianhydride, ) And a poly (amide-imide) copolymer obtained from a reaction product containing an aromatic dicarboxylic acid derivative has a high optical characteristic And further shows improved mechanical properties, thus completing the present invention.

Thus, one embodiment includes a reaction product of at least one tetracarboxylic dianhydride, at least one diamine, and at least one dicarboxylic acid derivative, wherein the at least one tetracarboxylic acid dianhydride has the formula Wherein the at least one diamine comprises a diamine represented by the following formula (2), and the at least one tetracarboxylic acid dianhydride includes a tetracarboxylic dianhydride represented by the following formula (3) (Amide-imide) copolymer comprising a carboxylic acid derivative and a carboxylic acid derivative:

[Chemical Formula 1]

In Formula 1, R ¹ is a substituted or unsubstituted quadrivalent C4 to C12 saturated or unsaturated aliphatic hydrocarbon ring group;

(2)

NH ₂ -R ² -NH ₂

In Formula 2,

R ² represents a substituted or unsubstituted C 6 to C 30 aromatic hydrocarbon ring group having 2 or more substituents, and the 2 or more substituted or unsubstituted C 6 to C 30 aromatic hydrocarbon ring groups are those in which two or more aromatic hydrocarbon rings are replaced by -O-, C (= O) -, -CH (OH) -, -S (= O) 2 -, - (CH 2) p - ( _{where, 1≤p≤10), - (CF 2} ) q - ( wherein, 1? Q? 10), -Si (C _n H _{2n + 1} ) ₂ -, -C (C _n H _{2n + 1} ) ₂ -, -C (C _n F _{2n + 1} ) ₂ - n? 10), -C (= O) NH-, or a combination thereof;

(3)

In Formula 3,

R ³ includes a substituted or unsubstituted C6 to C30 aromatic hydrocarbon ring group, and the substituted or unsubstituted C6 to C30 aromatic hydrocarbon ring group may include one aromatic hydrocarbon ring, or a ring in which two or more aromatic hydrocarbon rings are condensed Or two or more aromatic hydrocarbon rings or one or more aromatic hydrocarbon rings and one or more of said condensed rings may form a single bond, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -} (CH 2) p - ( _{where, 1≤p≤10), - (CF 2} ) q - ( _{where, 1≤q≤10), -Si (C n} H 2n + 1 _{) 2 -, -C (C n} H 2n + 1) 2 -, -C (C n F 2n + 1) 2 - ( wherein, 1≤n≤10), -C (= O ) NH- or a Connected by a combination,

X ¹ and X ² are each independently a halogen, a hydroxyl group, or an alkoxy group having from 1 to 4 carbon atoms.

In R ¹ of Formula 1, the substitution is such that at least one hydrogen atom of the saturated or unsaturated aliphatic hydrocarbon ring group is substituted with a hydroxyl group, a halogen group, a nitro group, a cyano group, a carboxyl group, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, A C1 to C20 alkoxy group, and a C1 to C20 acyl group, or a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C1 to C20 alkoxy group, or a C1 to C20 alkoxy group which is substituted by a substituent selected from the group consisting of C1 to C20 acyl groups, C1-C20 acyl group. For example, the C1 to C20 alkyl group substituted by the substituents may be a C1 to C20 alkyl group substituted with a halogen group, a C1 to C20 alkyl group substituted with a hydroxy group, a C1 to C20 alkyl group substituted with a nitro group, or a C1 To C20 alkyl groups, but is not limited thereto.

In R ² of Formula ² and R ³ of Formula 3, the substitution is such that at least one hydrogen atom of the aromatic hydrocarbon ring is substituted with a hydroxyl group, a halogen group, a nitro group, a cyano group, a carboxyl group, a C1 to C20 alkyl group, A C 1 to C 20 alkoxy group, a C 1 to C 20 acyl group, a C 1 to C 20 alkyl group substituted by a substituent selected from the group consisting of C 1 to C 20 acyl groups, or a C 2 to C 20 alkenyl group, , Or C1 to C20 acyl groups. For example, the C1 to C20 alkyl group substituted by the substituents may be a C1 to C20 alkyl group substituted with a halogen group, a C1 to C20 alkyl group substituted with a hydroxy group, a C1 to C20 alkyl group substituted with a nitro group, or a C1 To C20 alkyl groups, but is not limited thereto.

R ¹ in the above formula (1) may be selected from unsubstituted C4 to C8 tetravalent saturated aliphatic hydrocarbon ring groups, for example, ring groups represented by the following structural formula:

,

,

,

,

,

,

,

,

,

.

,

.

In one embodiment, R ¹ in Formula 1 may be an unsubstituted C 4 saturated aliphatic hydrocarbon ring group.

By incorporating the tetracarboxylic dianhydride represented by Formula 1, that is, the acid dianhydride containing a saturated or unsaturated aliphatic hydrocarbon ring group at the center, as the dianhydride component, the poly (amide-imide) The copolymers have the advantage of significantly improving mechanical properties, such as tensile modulus, compared to conventional poly (amide-imide) copolymers prepared with aromatic dianhydrides, Excellent optical properties can also be maintained. As will be described later, the acid dianhydride containing such an aliphatic hydrocarbon ring group is obtained by reacting an aromatic dicarboxylic acid derivative with an aromatic dicarboxylic acid derivative in a molar ratio of about 40 to 80: 60 to 20, for example, about 45 to 75: 55 to 25, For example, in a molar ratio of about 50 to 70: 50 to 30. The mixture of the acid dianhydride containing the aliphatic hydrocarbon ring group and the aromatic dicarboxylic acid derivative and the diamine containing the diamine represented by the formula (2) are reacted at a molar ratio of about 1: 1 to obtain the poly Amide-imide) copolymers can be prepared. The mixture of the tetracarboxylic dianhydride containing the tetracarboxylic acid dianhydride represented by the formula (1) and the diamine containing the diamine represented by the formula (2) in the above range is reacted with the aromatic dicarboxylic acid represented by the formula (3) (Amide-imide) copolymers prepared by reacting aromatic tetracarboxylic acid dianhydrides with aromatic tetracarboxylic acid dianhydrides and aromatic dicarboxylic acid derivatives, A poly (amide-imide) copolymer having improved mechanical properties such as tensile modulus can be produced while maintaining excellent optical properties.

R ² in Formula 2 is a group in which two or more substituted or unsubstituted phenylene groups are linked by -O-, -S-, -C (= O) - or -CH (OH) -, or more phenyl groups each _{independently, -OH, -CF 3, -CCl 3} , -CBr 3, -CI 3, -NO 2, -CN, -COCH _3, and from the group consisting of -CO ₂ C ₂ H ₅ May be substituted by a substituent selected.

R ² of the diamine represented by Formula 2 may be one in which at least two unsubstituted phenylene groups are linked by -O-, -S-, -C (= O) -, or -CH (OH) -.

The at least one diamine may further include a diamine represented by the following formula (2A) in addition to the diamine represented by the formula (2)

(2A)

NH _{2 -} R ^{2 '-} NH ₂

In the above formula (2A)

R ^{2 '} includes a group in which two or more substituted or unsubstituted C6 to C30 aromatic hydrocarbon rings are connected by a single bond.

R ^{2 '} of the diamine represented by the formula (2A) may be a group in which two or more phenylene groups each substituted with -CF ₃ , -CCl ₃ , or -CBr ₃ are linked by a single bond.

Wherein the at least one diamine is a diamine in which at least ^two phenylene groups substituted with -CF ₃ , -CCl ₃ , or -CBr ₃ are respectively linked by a single bond, and R ² in the formula (2) Or two or more of the phenylene groups may be linked by -O-, -S-, -C (= O) -, or -CH (OH) -.

The at least one diamine of the formula (2A) R ^{2 'is} -CF _3, each of the two phenylene groups are alkylene groups of two phenyl R ² is a diamine, and the general formula (2) are connected by a single bond -O- substituted by an unsubstituted , ≪ / RTI >

In one embodiment, the diamine is a diamine alkylene group is phenyl two R ^{2 'in} the formula (2A), each optionally substituted with -CF ₃ linked by a single bond, for example, (trifluoromethyl) 2,2'-bis benzidine (2,2'-bis (trifluoromethyl) benzidine : TFDB) and a diamine R ² is 2-phenylene unsubstituted group of the formula (2) linked by -O-, for example, 4,4'-octanoic And may contain 4.4'-oxydianiline (ODA).

In the diamine, the diamine represented by the formula (2) may contain less than the diamine represented by the formula (2A). For example, in the diamine, the diamine represented by Formula 2 and the diamine represented by Formula 2A may have a molar ratio of 30:70 to 1:99, for example, a molar ratio of 25:75 to 1:99, For example, a molar ratio of from 20:80 to 1:99, for example from 15:85 to 1:99, such as from 12:88 to 1:99, for example from 10:90 to 1 : 99, for example, in a molar ratio of 5:95 to 1:99, but is not limited thereto.

The diamine represented by Formula 2 may be contained in an amount of 30 mol% or less based on the total amount of the at least one diamine. For example, the diamine represented by the above formula (2) may be used in an amount of 25 mol% or less, for example, 20 mol% or less, for example, 15 mol% or less, for example, 10 mol% , For example, 5 mol% or less.

The diamine represented by the general formula (2) may include at least 0.1 mol% based on the total amount of the at least one diamine. For example, the diamine represented by Formula 2 may be used in an amount of 1 mol% or more, for example, 2 mol% or more, such as 3 mol% or more, for example, 4 mol% or more , For example, 5 mol% or more.

In one embodiment, the diamine represented by Formula 2 is contained in an amount of 0.1 mol% or more and 30 mol% or less, for example, 1 mol% or more and 30 mol% or less relative to the total amount of the at least one diamine, For example, 2 mol% or more and 25 mol% or less, for example, 3 mol% or more and 30 mol% or less, for example, From 3 mol% to 25 mol%, for example, from 3 mol% to 20 mol%, for example, from 4 mol% to 30 mol%, for example, from 4 mol% to 25 mol% For example, 4 mol% or more and 10 mol% or less, for example, 5 mol% or more and 30 mol% or less, for example, , For example, from 5 mol% to 25 mol%, for example, from 5 mol% to 20 mol%, for example, from 5 mol% to 15 mol%, for example, from 5 mol% %, ≪ / RTI >

In one embodiment, the diamine represented by the general formula (2) is a diamine in which two phenylene groups in which R ² is unsubstituted are linked by -O-, for example, 4,4'-oxydianiline (ODA) 30 mol% or less, for example, 20 mol% or less, for example, 10 mol% or less of the diamine content.

By including a diamine of the diamine, R ² is unsubstituted at least two phenylene groups represented by the above formula (2) linked by -O- to the content range, the poly is made therefrom - is (amide-imide) copolymer is the optical properties The mechanical properties can be further improved without decreasing. The diamine to which at least two phenylene groups in which R ² is unsubstituted is linked by -O- can impart flexibility to a poly (amide-imide) copolymer produced therefrom. When the amount of diamine to which two unsubstituted phenylene groups are linked by -O- is in excess of the above range, the effect of improving the mechanical properties of the poly (amide-imide) copolymer prepared therefrom is insignificant. On the other hand, The characteristics may be degraded.

On the other hand, R ^{2 '} of the diamine represented by the formula (2A) is a diamine in which two phenylene groups substituted with -CF ₃ in each ring are connected in a single bond, for example, 2,2'-bis (trifluoromethyl ) Benzidine (TFDB) has a rigid structure by connecting two phenylene groups by a single bond, and the aromatic ring is substituted with -CF ₃ to form a poly (amide- Imide) copolymer to improve the optical properties of the copolymer.

R ³ in Formula 3 may be an unsubstituted phenylene group, and X ¹ and X ² may each independently be -Cl, -OH, or -OCH _3. For example, X ¹ and X ² may all be -Cl Lt; / RTI >

The poly (amide-imide) copolymer is obtained by reacting a tetracarboxylic acid dianhydride containing a tetracarboxylic dianhydride represented by the formula (1), a diamine containing a diamine represented by the formula (2) A product obtained by reacting a dicarboxylic acid derivative containing a dicarboxylic acid derivative represented by a molar ratio of 40 to 80: 100: 60 to 20, respectively, for example, in a molar ratio of 50 to 70: 100: 50 to 30 . A tetracarboxylic acid dianhydride containing a tetracarboxylic acid dianhydride represented by the formula (1), a diamine including a diamine represented by the formula (2), and a dicarboxylic acid derivative represented by the formula (3) (Amide-imide) copolymer produced therefrom exhibits superior mechanical properties, for example, a high tensile modulus, and an excellent light transmittance and low yellowing degree YI) and the like can be maintained. For example, when a film having a thickness of about 50 탆 to 100 탆 is produced from a poly (amide-imide) copolymer produced from the above reaction, the tensile modulus of these films may be 6.5 GPa or more and 350 nm to 750 nm The light transmittance in the wavelength range may be 87.5% or more. Accordingly, such a poly (amide-imide) copolymer film can be advantageously used as a display device, particularly a window film of a flexible display device and the like.

The poly (amide-imide) copolymer according to one embodiment comprises a tetracarboxylic acid dianhydride containing a tetracarboxylic acid dianhydride represented by the formula (1), a diamine including a diamine represented by the formula (2) The dicarboxylic acid derivative containing the dicarboxylic acid derivative represented by the formula (3) may be prepared by copolymerizing the dicarboxylic acid derivative at the above-mentioned molar ratio in accordance with the production method of a known poly (amide-imide) copolymer. For example, an aromatic dicarboxylic acid derivative represented by the formula (3) and a diamine represented by the formula (2) are reacted to form an amide structural unit, and then the dianhydride represented by the formula (1) By further reaction, the formed amide structural unit and the amic acid structural unit are linked together with the formation of an amic acid structural unit by a diamine and a dianhydride to form a poly (amide-amic acid) copolymer. The poly (amide-amic acid) copolymer thus prepared may be partially or fully imidized by a chemical and / or thermal imidization process as required and may be subjected to precipitation, filtration, drying, and / or additional heat treatment (Amide-imide) copolymer by selectively carrying out the process.

Alternatively, the diamine represented by the formula (2) and the aromatic dicarboxylic acid derivative represented by the formula (3) are polymerized according to a known polyamide production method to prepare an oligomer having an amide structural unit capped at both terminals with an amino group (Amide-imide) copolymer may be prepared by reacting the produced oligomer with a dianhydride represented by the above formula (1) as a diamine monomer. At this time, the diamine of formula (2) may be added in excess to the dicarboxylic acid derivative of formula (3) so that both ends of the oligomer containing the amide structural unit are capped with an amino group. The poly (amide-imide) copolymer can be prepared by determining the amount of the dianhydride and the additional diamine to be used in the subsequent reaction and taking into account the amount of the amide structural unit in the oligomer having the amide structural unit thus prepared .

Compared with the method of producing a poly (amide-imide) copolymer in which the imide structural unit is formed continuously after the formation of the existing amide structural unit, the amide structure It is possible to omit the precipitation step for removing the byproducts such as hydrogen halide, for example, HCl, which is a byproduct produced during the unit formation, thereby shortening the entire process time and increasing the yield of the final product. Further, when the latter method is used, the content of the amide structural unit in the poly (amide-imide) copolymer may be further increased.

The poly (amide-imide) copolymer prepared as described above can be produced into a film using a known method. For example, in the case of producing a film according to the dry-wet process, a solution containing the poly (amide-imide) copolymer is extruded from a spinneret onto a support such as a drum, an endless belt or the like to form a film, The solvent is evaporated and dried until the film is self-retaining. The drying can be performed by elevating the temperature of the film to about room temperature, for example, from about 25 ° C to about 150 ° C within about one hour. Thereafter, the dried film is heated from room temperature to a temperature of about 250 ° C to about 300 ° C at a rate of about 10 ° C / min, and then the film is held at about 250 ° C to about 300 ° C for about 5 minutes to about 30 minutes, -Imide) copolymer film.

The membrane after the drying process is peeled from the support and introduced into the heat treatment process. In the heat treatment process, the film is heated while both ends are fixed. At this time, the length of both ends can be adjusted to stretch the film. The heat treatment may be performed at a temperature of from about 200 DEG C to about 500 DEG C, for example, from about 250 DEG C to about 400 DEG C for a few seconds to several minutes. The film after the heat treatment is preferably cooled slowly. For example, it is preferable to cool the film at a rate of about 50 DEG C / second or less. The film may be formed as a single layer or a plurality of layers.

The poly (amide-imide) copolymer film thus prepared has a tensile modulus of at least about 6.5 GPa as measured by ASTM D882 at a thickness of about 50 탆 to about 100 탆 and a wavelength range of 350 nm to 750 nm as measured by ASTM D1925 May have a light transmittance of about 87.5% or more.

For example, the tensile modulus may be within the above range, for example, about 6.7 GPa or more, within the above range, for example, about 6.9 GPa or more and within the above range, for example, about 7.0 GPa or more, It may be more than 7.2GPa. The tensile modulus may be within the above range, for example, from about 6.5 GPa to 20 GPa, and within this range, for example, from about 6.7 GPa to 20 GPa, and within this range, for example, from about 6.9 GPa to 15 GPa, Within the range, for example, from about 7.0 GPa to about 10 GPa, and within this range, for example, from about 7.5 GPa to about 10 GPa, and within this range, for example, from about 8.0 GPa to 10 GPa.

Also, YI may be less than one.

That is, the poly (amide-imide) copolymer according to one embodiment can maintain excellent optical properties while having excellent mechanical properties, for example, higher tensile modulus.

As described above, the poly (amide-imide) copolymer according to one embodiment has improved mechanical properties, for example, higher tensile modulus while maintaining excellent optical properties, A window film of a display device, and the like.

In another embodiment, the electronic device comprises a film comprising the poly (amide-imide) copolymer. The film can be used as a substrate of an electronic device, an insulating film, a dielectric film, a flat film, a protective film, a protective film or the like.

The electronic device can be a flat panel display, a touch panel, a solar cell, an e-window, a heat mirror, a transparent transistor, a flexible display, a complementary metal oxide semiconductor sensor, or a light emitting diode illumination.

Hereinafter, a flat panel display will be described as an example of an electronic device with reference to the drawings.

1 is a cross-sectional view of a display device according to an embodiment.

Referring to FIG. 1, a display device 100 according to an embodiment includes a display panel 50 and a window 10A.

The display panel 50 may be, for example, an organic light emitting display panel or a liquid crystal display panel, and may be, for example, a Ben double display panel, a foldable display panel, or a rollerable display panel.

The window 10A may comprise a poly (amide-imide) copolymer film as described above. The window 10A can be disposed on the observer side.

A further layer may be interposed between the display panel 50 and the window 10A and may further comprise, for example, a single layer or a plurality of polymeric layers (not shown) and optionally a transparent adhesive layer (not shown) have.

2 is a cross-sectional view of a display device according to another embodiment.

Referring to FIG. 2, the display device according to the present embodiment includes a display panel 50, a window 10A, and a touch screen panel 70 positioned between the display panel 50 and the window 10A.

The display panel 50 may be, for example, an organic light emitting display panel or a liquid crystal display panel, and may be, for example, a Ben double display panel, a foldable display panel, or a rollerable display panel.

The window 10A may comprise a poly (amide-imide) copolymer film as described above. The window 10A can be disposed on the observer side.

The touch screen panel 70 is disposed adjacent to the window 10A and the display panel 50 and recognizes the change of the touch position and position when a human hand or an object is touched through the window 10A and outputs a touch signal . The driving module (not shown) can check the position of the touch point from the output touch signal, check the icon displayed at the position of the detected touch point, and perform a function corresponding to the checked icon, Can be displayed on the display panel 50.

Other layers may be interposed between the touch screen panel 70 and the window 10A and may further include, for example, a single layer or multiple layers of polymeric layers (not shown) and optionally a transparent bonding layer (not shown) have.

The display device can be applied to various electronic devices, for example, smart phones, tablet PCs, cameras, touch screen devices, and the like, but is not limited thereto.

Hereinafter, the embodiments will be described in more detail by way of examples and comparative examples. The following examples and comparative examples are for illustrative purposes only, and the scope of the present invention is not limited thereby.

Example

Synthesis Example 1: Preparation of oligomer A0-70 containing 70 mol% of amide structural unit

(2, 2'-bis (trifluoromethyl) benzidine) is bonded to both ends of TPCL according to the following Reaction Scheme 1 to form an amide structure unit Containing oligomers are prepared:

(Scheme 1)

Namely, 177 g of N, N-dimethylacetamide (DMAc) was charged into a 250-ml reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while passing nitrogen, After adjusting to 25 캜, 9.04 g of 2,2'-bis (trifluoromethyl) benzidine (TFDB) is dissolved. After 6.2 g of pyridine was added thereto, 3.99 g of terephthaloylchloride (TPCl) was slowly added thereto. When the addition is complete, set the temperature to 40 ° C and react sufficiently. After completion of the reaction, the mixture is precipitated with a 5% aqueous NaCl solution, filtered, and dried in a vacuum oven at 80 ° C to obtain a white powder.

The obtained powder is an oligomer having an amide structure unit in which both terminals are capped with an amino group as shown in the above-mentioned Reaction Scheme 1, and this is hereinafter referred to as " AO-70 ". The A0-70 oligomer is used to polymerize the poly (amide-imide) copolymer in the following. It is possible to calculate the content of each monomer to be reacted in each of the following Examples and Comparative Examples in consideration of the fact that the n value which is the number of the average amide structural units in the A0-70 oligomer is 2.33.

Example 1: Preparation of poly (amide-amic acid) copolymer

N, N-dimethylacetamide (DMAc) (168 g) was charged into a 250-ml reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while passing nitrogen, 8.6 g of AO-70 is added. The temperature of the reactor was adjusted to 25 ° C, and 2,2'-bis (trifluoromethyl) benzidine (TFDB) and 4,4'-oxydianiline : ODA) were added in amounts of 1.34 g and 1.4 g, respectively. Thereafter, 10.5 g of cyclobutane tetracarboxylic dianhydride (CBDA) was added thereto, followed by dissolution and reaction with stirring. At this time, the temperature of the solution is maintained at 25 占 폚. After the reaction is complete, a poly (amide-amic acid) copolymer solution having a solids concentration of about 16% by weight is obtained therefrom.

Example 2: Preparation of poly (amide-amic acid) copolymer

The same procedure as in Example 1 was carried out except that the content of TPCL was adjusted to 0.4 molar equivalent and the content of oligomer AO-70 obtained in Synthesis Example was controlled so that the content of CBDA was adjusted to 0.6 molar equivalent To prepare a poly (amide-amic acid) copolymer solution.

Example 3: Preparation of poly (amide-amic acid) copolymer

The same procedure as in Example 1 was used except that the content of TPCL was adjusted to 0.5 molar equivalent and the content of oligomer A0-70 obtained in the above Synthesis Example was controlled and the content of CBDA was adjusted to 0.5 molar equivalent To prepare a poly (amide-imide) copolymer solution.

Example 4: Preparation of poly (amide-amic acid) copolymer

The content of the oligomer A0-70 obtained in the above Synthesis Example was adjusted so that the content of TPCL became 0.5 molar equivalent, the content of TFDB and ODA was adjusted to have a molar ratio of 9: 1, and the content of CBDA was adjusted to be 0.5 molar equivalent (Amide-imide) copolymer solution was prepared in the same manner as in Example 1, except that the poly (amide-imide) copolymer solution was used.

Example 5: Preparation of poly (amide-amic acid) copolymer

A poly (amide-imide) copolymer solution was prepared using the same method as in Example 1 except that the molar ratio of TFDB to ODA was 9: 1.

Example 6: Preparation of poly (amide-amic acid) copolymer

The procedure of Example 1 was repeated except that the molar ratio of TFDB to ODA was adjusted to be 9: 1 and TPCL was adjusted to be 0.4 molar equivalent and CBDA to 0.6 molar equivalent, ) Copolymer solution was prepared.

Comparative Example 1: Preparation of poly (amide-amic acid) copolymer

Except that the amount of the A0-70 oligomer prepared in the above Synthesis Example was controlled so as to include 1 molar equivalent of the TFDB alone component and 0.5 molar equivalent of TPCL as the diamine, 1 was used to prepare a poly (amide-imide) copolymer solution.

Comparative Example 2: Preparation of poly (amide-amic acid) copolymer

Except that the amount of the A0-70 oligomer prepared in the above Synthesis Example was controlled so that the diamine contained 1 mole equivalent of TFDB alone and 0.4 mole equivalent of TPCL and that the CBDA was adjusted to include 0.6 mole equivalent, 1 was used to prepare a poly (amide-imide) copolymer solution.

Comparative Example 3: Preparation of poly (amide-amic acid) copolymer

Except that the amount of the A0-70 oligomer prepared in the above Synthesis Example was controlled so that 1 mole equivalent of the TFDB alone component and 0.3 mole equivalent of TPCL were contained as the diamine and that the CBDA was adjusted to include 0.7 mole equivalent, 1 was used to prepare a poly (amide-imide) copolymer solution.

Comparative Example 4: Production of polyamic acid

As a reactor, 162 g of N, N-dimethylacetamide (DMAc) was added while passing nitrogen through a 250-ml reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a condenser. The temperature of the reactor is set at 40 占 폚. Then, 13.75 g and 2.15 g of TFDB and ODA, respectively, are added. After confirming that both diamines are completely dissolved, 7.37 g of CBDA is added. When all the CBDA is dissolved, 4.74 g of BPDA (3,3 ', 4,4'-biphenyl tetracarboxylic dianhydride) is added. 10 g of DMAc is used to clean the material in the vessel and reactor. After completion of the dissolution, the reaction is terminated after further reaction for 24 hours.

Comparative Example 5: Preparation of poly (amide-amic acid) copolymer

The amount of the A0-70 oligomer prepared in the above Synthesis Example was controlled so that 1 mole equivalent of TFDB alone component and 0.3 mole equivalent of TPCL as diamine were contained, and 0.5 mole equivalent of CBDA, which is an aliphatic acid dianhydride, and an aromatic acid dianhydride The procedure of Example 1 was repeated except that the amount of 4,4'-oxydiphthalic tetracarboxylic dianhydride (ODPA) was adjusted to include 0.2 molar equivalent of 4,4'-oxydiphthalic tetracarboxylic dianhydride (ODPA) Methacrylic acid copolymer) solution.

Preparation Examples and Evaluation: Preparation and evaluation of poly (amide-imide) copolymer films

50 g each of the poly (amide-imide) copolymer solution obtained in each of the above Examples and Comparative Examples was taken, and 4.1 g of acetic anhydride was added thereto, followed by stirring for 30 minutes. Then 0.4 g of pyridine are mixed and each solution is cast onto glass using a doctor blade before the polymer is cured. The cast solution is heat treated on a 130 ° C hot plate for 30 minutes. Thereafter, the film was peeled off from the glass and fixed to the frame, and then heated at a rate of 10 ° C / min and heat-treated at 260 ° C for 20 minutes.

The composition, tensile modulus, yellowness (YI) and transmittance of the thus obtained film were measured, and the results are shown in Table 1 below.

Here, the yellowness degree and the transmittance were measured using a Minolta spectrocolorimeter CM-3600d based on a 50 탆 thick film and taken as ASTM D1925.

The tensile modulus was measured using ASTM D882.

CBDA TPCl BPDA ODPA TFDB ROOM thickness
(탆) Modulus (GPa) YI Transmittance @ 350 to 750 nm Example 1 70 30 - - 80 20 47 6.5 2.5 88.9% Example 2 60 40 - - 80 20 47 6.7 3.2 88.7% Example 3 50 50 - - 80 20 49 6.9 4.9 87.7% Example 4 50 50 - - 90 10 49 7.5 3.3 88.4% Example 5 70 30 - - 90 10 45 7.0 2.7 89.1% Example 6 60 40 - - 90 10 48 7.0 2.9 88.8% Comparative Example 1 50 50 - - 100 - 50 Brittle Comparative Example 2 60 40 - - 100 - 49 Brittle Comparative Example 3 70 30 - - 100 - 49 Brittle Comparative Example 4 70 - 30 - 80 20 49 5.7 6.2 88.6% Comparative Example 5 50 30 - 20 100 - 48 5.9 3.5 89.3%

As shown in the above Table 1, a preparation made from a composition comprising a dianhydride containing an aliphatic saturated hydrocarbon ring group as a dianhydride component and a diamine linked by -O- groups in which two or more aromatic rings as diamines impart flexibility The poly (amide-imide) copolymers according to Examples 1 to 6 all exhibit a high tensile modulus of 6.5 GPa or more.

On the other hand, compared with Examples 1 to 3, comparative examples prepared from compositions which are the same as dianhydride and aromatic dicarboxylic acid components but which do not contain a diamine in which two or more aromatic rings as diamines are linked by -O- groups giving flexibility The poly (amide-imide) copolymers according to Examples 1 to 3 were too brittle to form films themselves. That is, when an aliphatic dianhydride is included as a dianhydride component, mechanical properties such as tensile modulus can be increased, but it is understood that additional components are required to impart flexibility to the film.

On the other hand, in the case of the polyimide film according to Comparative Example 4 containing a diamine dianhydride as an aliphatic dianhydride component and a diamine having two or more aromatic rings linked by -O- groups giving flexibility, Despite the fact that BPDA having a rigid structure as an additional dianhydride instead of a carboxylic acid derivative was prepared, the tensile modulus of the film prepared therefrom was much lower than the tensile modulus of the films of Examples 1 to 6 Able to know. That is, it can be seen that the mechanical properties of the poly (amide-imide) copolymer film prepared using a mixture of an aliphatic dianhydride and an aromatic dicarboxylic acid derivative are higher than that of a polyimide film.

The total content of the aliphatic dianhydride and the aromatic dicarboxylic acid derivative is lower than the content of the aliphatic dianhydride and the aromatic dicarboxylic acid derivative used in Examples 1 to 6 and the two aromatic rings have flexibility The poly (amide-imide) prepared according to Comparative Example 5, which additionally contains ODPA, which is a dianhydride connected by -O- group and diamine, does not contain diamines connected by flexible linkages of two aromatic rings ) ≪ / RTI > copolymer film, the tensile modulus is lower than that of the films according to Examples 1-6.

On the other hand, the poly (amide-imide) copolymer film according to Examples 1 to 6 exhibits a high transmittance of 87.7% or more in the wavelength range of 350 to 750 nm and exhibits a low yellowing degree of not more than 4.9, (Amide-imide) copolymer film according to Examples 1 to 6 was superior to the polyimide film according to Comparative Example 4 in optical properties as well, with a transmittance of 88.6% and a yellowness degree of 6.2, . That is, the poly (amide-imide) copolymer film according to Examples 1 to 6 is superior in both mechanical characteristics and optical characteristics to the polyimide film of Comparative Example 4.

As described above, the poly (amide-imide) copolymer according to one embodiment has much improved mechanical properties while maintaining excellent optical properties of conventional poly (amide-imide) copolymers, In particular, it can be advantageously used for a window film of a flexible display device.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And it goes without saying that the invention belongs to the scope of the invention.

Claims (21)

A reaction product of at least one tetracarboxylic dianhydride, at least one diamine, and at least one dicarboxylic acid derivative,
Wherein the at least one tetracarboxylic dianhydride comprises a tetracarboxylic dianhydride represented by the following Formula 1, the at least one diamine comprises a diamine represented by Formula 2, and the at least one dicar (Amide-imide) copolymer comprising a dicarboxylic acid derivative represented by the following formula (3): < EMI ID =
[Chemical Formula 1]

In Formula 1, R ¹ is a substituted or unsubstituted quadrivalent C4 to C12 saturated or unsaturated aliphatic hydrocarbon ring group;
(2)
NH ₂ -R ² -NH ₂
In Formula 2,
R ² comprises at least two substituted or unsubstituted C 6 to C 30 aromatic hydrocarbon ring groups, and the at least two substituted or unsubstituted aromatic hydrocarbon ring groups are those in which at least two aromatic rings are replaced by -O-, -S-, -C (= O ) -, -CH (OH) - , -S (= O) 2 -, - (CH 2) p - ( _{where, 1≤p≤10), - (CF 2} ) q - ( wherein, 1≤q≤ _{10), -Si (C n H} 2n + 1) 2 -, -C (C n H 2n + 1) 2 -, -C (C n F 2n + 1) 2 - ( wherein, 1≤n≤10) , -C (= O) NH-, or a combination thereof;
(3)

In Formula 3,
R ³ includes a substituted or unsubstituted C6 to C30 aromatic hydrocarbon ring group, and the substituted or unsubstituted C6 to C30 aromatic hydrocarbon ring group may include one aromatic hydrocarbon ring, or a ring in which two or more aromatic hydrocarbon rings are condensed Or two or more aromatic hydrocarbon rings or one or more aromatic hydrocarbon rings and one or more of said condensed rings may form a single bond, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -} (CH 2) p - ( _{where, 1≤p≤10), - (CF 2} ) q - ( _{where, 1≤q≤10), -Si (C n} H 2n + 1 _{) 2 -, -C (C n} H 2n + 1) 2 -, -C (C n F 2n + 1) 2 - ( wherein, 1≤n≤10), -C (= O ) NH- or a Connected by a combination,
X ¹ and X ² are each independently a halogen, a hydroxyl group, or an alkoxy group having from 1 to 4 carbon atoms. The poly (amide-imide) copolymer according to claim 1, wherein R ¹ in the formula (1) is an unsubstituted C4 to C8 tetravalent saturated aliphatic hydrocarbon ring group. In claim 1, R ² of Formula 2 is alkylene group substituted or unsubstituted at least two phenyl -O-, -S-, -C (= O ) - and is connected by a -, or -CH (OH) the two or more of substituted phenyl groups are each _{independently, -OH, -CF 3, -CCl 3} , -CBr 3, -CI 3, -NO 2, -CN, -COCH 3 or -CO ₂ C ₂ H It would be substituted by substituents selected from ₅ poly (amide-imide) copolymer. 2. The poly (amide-imide) copolymer according to claim 1, wherein the diamine further comprises a diamine represented by the following formula (2A): <
(2A)
NH _{2 -} R ^{2 '-} NH ₂
In the above formula (2A)
R ^{2 '} includes a group in which two or more substituted or unsubstituted aromatic hydrocarbon rings are connected by a single bond. In claim 4, wherein R ² is the formula 2A ^'is alkylene group of two or more substituted or unsubstituted phenyl linked to the single bond, the substituted two or more phenylene groups, each independently selected from -CF _3, -CCl _3, or - Wherein the poly (amide-imide) copolymer is substituted with CBr ₃ . Wherein the at least one diamine comprises the diamine represented by the formula (2A) and the diamine represented by the formula (2), and the R ^{2 '} of the diamine represented by the formula (2A) Wherein the substituted two or more phenylene groups are each independently substituted with -CF ₃ , -CCl ₃ , or -CBr ₃ , and the diamine represented by the general formula (2) is an unsubstituted or substituted two or more phenylene (Amide-imide) copolymers wherein the groups are connected by a group -O-, S-, -C (= O) -, or -CH (OH) -. [5] The method of claim 4, wherein the at least one diamine comprises the diamine represented by the formula (2A) and the diamine represented by the formula (2), and the R ^{2 '} Wherein said substitution is each substituted with -CF ₃ , and R ² in said formula (2) is a poly (amide-imide) copolymer in which two unsubstituted phenylene groups are linked by -O- . 5. The poly (amide-imide) copolymer according to claim 4, wherein the diamine represented by Formula 2 is contained less than the diamine represented by Formula 2A. The poly (amide-imide) copolymer according to claim 4, wherein the diamine represented by Formula 2 and the diamine represented by Formula 2A are contained in the molar ratio of 30:70 to 1:99 relative to the diamine. The poly (amide-imide) copolymer according to claim 1, wherein the diamine represented by Formula 2 is contained in an amount of 30 mol% or less based on the total amount of the diamine. The poly (amide-imide) copolymer according to claim 1, wherein the diamine represented by Formula 2 is contained in an amount of 20 mol% or less based on the total amount of the diamine. The poly (amide-imide) copolymer according to claim 1, wherein the diamine represented by Formula 2 is contained in an amount of 10 mol% or less based on the total amount of the diamine. The poly (amide-imide) copolymer according to claim ¹ , wherein R ³ in Formula 3 is an unsubstituted phenylene group, and X ¹ and X ² are each independently -Cl, -OH, or -OCH ₃ . The poly (amide-imide) copolymer according to claim 1, wherein R ¹ in the formula (1) is an unsubstituted C4 saturated aliphatic hydrocarbon ring group. The poly (amide-imide) copolymer of claim 1, wherein the tetracarboxylic dianhydride, the diamine, and the dicarboxylic acid derivative are reacted at a molar ratio of 40 to 80: 100: 60 to 20, respectively, The resulting product, poly (amide-imide) copolymer. The method of claim 1, wherein the poly (amide-imide) copolymer is reacted with the tetracarboxylic dianhydride, the diamine, and the dicarboxylic acid derivative in a molar ratio of 50 to 70: 100: 50 to 30, The resulting product, poly (amide-imide) copolymer. A molded article comprising the poly (amide-imide) copolymer according to any one of claims 1 to 16. The molded article as claimed in claim 17, wherein the molded article is a film having a tensile modulus of 6.5 GPa or more at a thickness of 50 to 100 占 퐉 and a transmittance of 87.5% or more at a wavelength of 350 nm to 750 nm. A window for a display device comprising a polymeric film comprising a poly (amide-imide) copolymer according to any one of claims 1 to 16. A display device comprising a molded article according to claim 17. 21. The display device according to claim 20, wherein the display device is a flexible display device.

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